GDB-Protocol: QBaud=<rate> set the baud rate of the remote target

[Andrew Cagney]

This packet replaces the unofficial ``b<hex-rate>'' packet.  The format
is:

	<- QBaud=<rate>
	-> OK

	<-> both local/remote change their baud rate

<rate> is in decimal.  I _can't_ see a reason for encoding the value in
hex.  In addition, GDB's ``set remotebaud'' command in conjunction with
an additional target-vector are reserved for this.

Pragmatics: we've got `b<rate>' and `b<breakpoint>' out there in the
field....

	Andrew